In a conventional distributed network, because a network device has neither a global service nor path information, a conventional constrained shortest path first (Constrained Shortest Path First, CSPF for short) algorithm is generally used to calculate a route, which, however, cannot implement optimized deployment of entire network services and maximization of a network utilization ratio.
In a software defined networking (Software Defined Networking, SDN for short) technology, the optimized deployment of network services may be implemented by means of centralized control performed on a network by a controller and by using a global optimization algorithm (Global Optimization Algorithm, GOA for short). However, a proper rerouting sequence planning algorithm is required to implement seamless or hitless switching from an initial network state to a final network state.
In the prior art 1, a proper adjustment sequence of switching from an initial network state to a final network state is found by using error trial and fallback as a core idea. However, time performance of this algorithm is on an exponential scale, and online application in a network is impracticable.
In the prior art 2, direct adjustment from an initial network state to a final network state is required. In this case, a relatively high requirement is imposed on a current network utilization ratio, and a relatively high success ratio is possible only in a network state in which the network utilization ratio is relatively low. However, because most routing algorithms include the GOA algorithm of SDN, in calculating a path, a path that requires a smallest cost is always selected preferentially. Consequently, paths of most services are concentrated on a part of links, which reduces the success ratio of rerouting sequence planning and imposes a higher requirement on the network utilization ratio.